Shaped like an irregular triangle, Darjeeling district has a total geographical area of 3,149 sq kms. Its northern boundary extends up to the high altitude Phalut (3657 m), the junction of boundaries of Nepal and Sikkim.
This boundary runs east from Phalut along a ridge descending to the Ramam river and then joins Rangit river and finally mergers with River Teesta.
On the west, the district is bounded by Nepal. On the south lies the district of Purnea and West Dinajpur intercepted by the Mahananda river and on the east, the district is bounded by Bangladesh and the Jalpaiguri district.
The district is basically a portion of the lower Himalayas with a flat territory at the base of the hills known as the Tarai. The Tarai is only 91 meters high above the sea level, but there are parts of the district in the hills which are nearly 3657.6 meters high.
The hill portion of the district is like a labyrinth of ridge and narrow valleys. There are no open valleys or plains or lakes. Most of the ridges are forest clad and in the lower slopes, tea plantation and crop cultivation are done.

The Darjeeling district is blessed with a great variation of climate largely due its different climatic zones. The district consists of two distinct tracts, the ridges and deep valley of lower Himalayas and the altitude varies between 300 m - 3,600 m.
In the Teesta valley, the climate is subtropical while in the hills, it is temperate and climate is dictated by altitude as one climbs above the Darjeeling hills.
The rainy months are June to September when most of the rainfall occur with appreciable amounts in May and October as well.
The winter in Darjeeling is extremely cold and extends from December to March. The summer spreads from April to mid June and during this period Darjeeling is delightfully cool.
The mean maximum temperature is approximately 11.1degree celsius and minimum temperature is 1.7 degree celsius.

The natural forests of Darjeeling range from tropical semi-evergreen forest, tropical moist deciduous forest, sub-tropical forest, Eastern Himalayan Wet temperate forest, and alpine forest according to their altitudes.
Besides these natural covers, man made forests are also found. The valuable indigenous species form the main component of the plantation in the district. An exotic conifer, Cryptomeria japonica, has done exceedingly well in the hill forests of the Darjeeling district. Other exotic conifers like Pinus petula, Cupressus species etc. have also shown great promise in the region.
According to a report published in 1993 by the State government, extent of dense forests and open forests in Darjeeling district amounts to 1093 sq.km and 362 sq.km respectively and the total forest cover is assessed at 1455 sq.km in the district.